Intention of troubleshooting procedure

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

Step 1-4
- Perform an inspection of the HO2S signal line-related parts.
Step 5-6
- Verify the condition of the HO2S installation and perform a unit inspection.
Step 7
- Perform an exhaust system parts inspection.
Step 8
- Perform an inspection of the engine compression.
Step 9
- Perform an inspection of the HO2S heater.
Repair completion verification
- Verify that the primary malfunction is resolved and there are no other malfunctions.

TROUBLESHOOTING DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	PURPOSE: INSPECT HO2S CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .) Are the connector and terminal normal?	Yes	Go to the next step.
1		No	Repair or replace the malfunctioning location and perform the repair completion verification.
2	PURPOSE: INSPECT PCM CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .) Are the connector and terminal normal?	Yes	Go to the next step.
2		No	Repair or replace the malfunctioning location and perform the repair completion verification.
3	PURPOSE: INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO GROUND Inspect the applicable circuit for a short to ground. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning location and perform the repair completion verification.
4	PURPOSE: INSPECT HO2S SIGNAL CIRCUIT FOR OPEN CIRCUIT Inspect the applicable circuit for open circuit. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning location and perform the repair completion verification.
5	PURPOSE: VERIFY IF HO2S IS INSTALLED CORRECTLY Verify the HO2S installation condition. (Installation angle, tightening torque value) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN L) .) Is the installation condition normal?	Yes	Go to the next step.
5		No	Correctly install the HO2S and perform the repair completion verification. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN L) .)
6	PURPOSE: INSPECT HO2S FOR MALFUNCTION Inspect the applicable part. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) INSPECTION (VIN L) .) Is the part normal?	Yes	Go to the next step.
6		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN L) .)
7	PURPOSE: VERIFY IF MALFUNCTION RELATED TO EMISSION SYSTEM AFFECTS HO2S SIGNAL Verify the exhaust gas leakage from the exhaust system. (between A/F sensor and HO2S) Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification.
7		No	Go to the next step.
8	PURPOSE: VERIFY IF MALFUNCTION RELATED TO ENGINE COMPRESSION AFFECTS DIAGNOSTIC RESULTS Inspect the engine compression. (See COMPRESSION INSPECTION (VIN M) .) (See COMPRESSION INSPECTION (VIN L) .) Are compression pressures within specification?	Yes	Go to the next step.
8		No	Replace or overhaul the engine and perform the repair completion verification.
9	PURPOSE: INSPECT HO2S HEATER FOR MALFUNCTION Inspect the applicable part. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) INSPECTION (VIN L) .) Is the part normal?	Yes	Go to the next step.
9		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN M) .) (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION (VIN L) .)
Repair completion verification 1	PURPOSE: VERIFY THAT VEHICLE IS REPAIRED Install/connect the part removed/disconnected during the troubleshooting procedure. Clear the DTC recorded in the memory. (See CLEARING DTC .) Replicate the vehicle conditions at the time the DTC was detected using the following procedure. Implement the repeatability verification procedure. (See REPEATABILITY VERIFICATION PROCEDURE .) Perform the DTC inspection for the PCM. (See DTC INSPECTION .) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION (VIN M) .) (See PCM REMOVAL/INSTALLATION (VIN L) .)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	PURPOSE: VERIFY IF OTHER DTCs DISPLAYED Perform the DTC inspection. (See DTC INSPECTION .) Are any other DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.